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<title>Problem 1620. -- [Usaco2008 Nov]Time Management -- 衡阳八中OJ离线版-2012-02-29</title><center><h2>1620: [Usaco2008 Nov]Time Management</h2><span class=green>Time Limit: </span>5 Sec&nbsp;&nbsp;<span class=green>Memory Limit: </span>64 MB<br><span class=green>Submit: </span>220&nbsp;&nbsp;<span class=green>Solved: </span>127<br>[<a href='submitpage.php?id=1620'>Submit</a>][<a href='problemstatus.php?id=1620'>Status</a>][<a href='bbs.php?id=1620'>Discuss</a>]</center><h2>Description</h2><div class=content>Ever the maturing businessman, Farmer John realizes that he must
manage his time effectively. He has N jobs conveniently numbered
1..N (1 <= N <= 1,000) to accomplish (like milking the cows, cleaning
the barn, mending the fences, and so on).

To manage his time effectively, he has created a list of the jobs
that must be finished. Job i requires a certain amount of time T_i
(1 <= T_i <= 1,000) to complete and furthermore must be finished
by time S_i (1 <= S_i <= 1,000,000). Farmer John starts his day at
time t=0 and can only work on one job at a time until it is finished.

Even a maturing businessman likes to sleep late; help Farmer John
determine the latest he can start working and still finish all the
jobs on time.


N个工作,每个工作其所需时间,及完成的Deadline,问要完成所有工作,最迟要什么时候开始.
</div><h2>Input</h2><div class=content>* Line 1: A single integer: N

* Lines 2..N+1: Line i+1 contains two space-separated integers: T_i
        and S_i

</div><h2>Output</h2><div class=content>* Line 1: The latest time Farmer John can start working or -1 if
        Farmer John cannot finish all the jobs on time.

</div><h2>Sample Input</h2>
			<div class=content><span class=sampledata>4<br />
3 5<br />
8 14<br />
5 20<br />
1 16<br />
<br />
INPUT DETAILS:<br />
<br />
Farmer John has 4 jobs to do, which take 3, 8, 5, and 1 units of<br />
time, respectively, and must be completed by time 5, 14, 20, and<br />
16, respectively.<br />
<br />
</span></div><h2>Sample Output</h2>
			<div class=content><span class=sampledata>2<br />
<br />
OUTPUT DETAILS:<br />
<br />
Farmer John must start the first job at time 2. Then he can do<br />
the second, fourth, and third jobs in that order to finish on time.<br />
</span></div><h2>HINT</h2>
			<div class=content><p></p></div><h2>Source</h2>
			<div class=content><p><a href='problemset.html?search=Silver'>Silver</a></p></div><center>[<a href='submitpage.php?id=1620'>Submit</a>][<a href='problemstatus.php?id=1620'>Status</a>][<a href='bbs.php?id=1620'>Discuss</a>]</center>﻿<br>

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